Kyrgios, out of sorts as he dropped the first set, complained to trainers that he was feeling ill.

But he steeled himself to continue and all distractions were forgotten as he rallied from 6-3 down in the third-set tiebreaker to subdue the 17-time Grand Slam champion from Spain.
Nadal, winner in Acapulco in 2005 and 2013, was playing his first event since falling in the Australian Open final to Novak Djokovic.

He had chances to break Kyrgios in both the second and third sets but was unable to convert as both sets went on serve to the tiebreakers.

Kyrgios leveled his head-to-head record with Nadal at 3-3 and will play three-time Grand Slam champion Stan Wawrinka for a place in the semi-finals.